docs: def message(self, do_html=True, custom_email_template=None):
          """
          Returns a tuple with (text_message,html_message)
          """
          context = {
              'build': self.build,
              'important_metadata': self.important_metadata,
              'metadata': self.metadata,
              'notification': self,
              'previous_build': self.previous_build,
              'regressions_grouped_by_suite': self.comparison.regressions_grouped_by_suite,
              'fixes_grouped_by_suite': self.comparison.fixes_grouped_by_suite,
              'known_issues': self.known_issues,
              'regressions': self.comparison.regressions,
              'fixes': self.comparison.fixes,
              'thresholds': self.thresholds,
              'settings': settings,
              'summary': self.summary,
          }
  
          html_message = ''
          if custom_email_template:
              text_template = jinja2.from_string(custom_email_template.plain_text)
              text_message = text_template.render(context)
  
              if do_html:
                  html_template = jinja2.from_string(custom_email_template.html)
                  html_message = html_template.render(context)
          else:
              text_message = render_to_string(
                  'squad/notification/diff.txt.jinja2',
                  context=context,
              )
              if do_html:
                  html_message = render_to_string(
                      'squad/notification/diff.html.jinja2',
                      context=context,
                  )
          return (text_message, html_message)